Variable expressivity and epigenetics
Part 1. Genetics
Short Specialist Review
Published Online: 15 JUL 2005
Copyright © 2005 John Wiley & Sons, Ltd
Encyclopedia of Genetics, Genomics, Proteomics and Bioinformatics
How to Cite
Blewitt, M. E. and Whitelaw, E. 2005. Variable expressivity and epigenetics. Encyclopedia of Genetics, Genomics, Proteomics and Bioinformatics. 1:1.3:36.
- Published Online: 15 JUL 2005
There is an increasing awareness that some genes do not behave in a strictly Mendelian fashion. In plants, flies, and mice, some alleles have been identified where the activity state varies among cells of the same cell type (termed variegation) and among genetically identical individuals (variable expressivity). We now know that this is the result of the stochastic establishment of differential epigenetic states at the locus. These states are set up during early development and are stably inherited for the life of the organism. While, in general, the states are cleared between generations, this is not always the case. Some alleles, now referred to as metastable epialleles, are not completely cleared from one generation to the next, resulting in a phenomenon termed transgenerational epigenetic inheritance. One of the interesting questions that arises from these findings is whether this mechanism has been involved in the evolution of morphological traits.
- variable expressivity;
- parent-of-origin effect;
- epigenetic inheritance;